Today, Americans pause to honor the late Martin Luther King Jr. and, for the second time, to inaugurate our nation’s first black president (although to comply with constitutional requirements Barack Obama formally took the oath of office yesterday).

At the time of King’s greatest achievements and, sadly, his 1968 assassination, few Americans were ready to believe that voters later would twice elect a black man as president of these United States. Back then, the nation was still coming to terms with the concept of racial desegregation and equality, concepts vigorously (and often violently) opposed by many whites, and not just in the South. The unhappy truth is that anti-black violence was far too common in supposedly enlightened cities such as Boston.

But that’s history, right? America’s schools and colleges have been desegregated for years now and that admirable fact is more or less taken for granted by most of us. If we follow college or professional football these days, as so many of us do, we surely must notice that many of the players are black.

Remember this, though: In 1959 Alabama — the same college football team that earlier this month won the national championship — was chosen to play in the Liberty Bowl against Penn State. Yet members of the Alabama board of trustees threatened to boycott the game simply because Penn State had black players on its team. That’s how absurd thinking was at the time.

Even eight years later, when five blacks tried to make Alabama’s football team, none of them succeeded. However, the Alabama coach, the legendary Paul “Bear” Bryant, had coached black players at the University of Maryland and he wanted to recruit blacks to play for his team. The university’s administrators and even the team’s fans objected strenuously.

In 1970, 12 years after King’s death, some northern universities refused to play Alabama because they did not want to play a team still entrenched in segregation. But Bryant persuaded the University of Southern California (USC) to travel to Alabama and that game — a 42-21 win for the integrated visiting team — stunned the ‘Bama fans and ultimately changed everything.

“I can’t thank you enough for what you did for me today,” Bryant, the losing coach, reportedly told the winning coach, John McKay. Bryant needed his team’s followers — and the university’s leadership — to see for themselves how the several black athletes on the visiting team had made a positive contribution to the game.

And there was this, too: Most black people in Alabama that day were rooting for USC. When the visiting team’s bus drove through the black sections of Tuscaloosa, people lined the streets to cheer them on. They refused to support their local team only because the local university wouldn’t let any of their race play for it.

But losing to USC broke the pattern. The very next season Alabama had its first black player and since then Alabama has won several national championships and many, if not most, of their star players have been blacks. And that’s true of all the major southern college football teams.

Although we don’t normally associate Martin Luther King with sports, his leadership in achieving desegregation and racial equality surely encouraged white men like Bryant to seek their own significant breakthroughs.

Even so, many Americans still express anger that a black man occupies the White House. The Southern Law Poverty Center reported that last year it had identified 1,018 active hate groups. Unfortunately, neither King nor Obama changed those who stubbornly refuse to accept the virtues and the fairness of racial tolerance and understanding.